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The type locality of this iridium anomaly is near Raton, New Mexico. [1] [2]Iridium is a very rare element in the Earth's crust, but is found in anomalously high concentrations (around 100 times greater than normal) in a thin worldwide layer of clay marking the boundary between the Cretaceous and Paleogene periods, 66 million years ago.
The Earth's crust is one "reservoir" for measurements of abundance. A reservoir is any large body to be studied as unit, like the ocean, atmosphere, mantle or crust. Different reservoirs may have different relative amounts of each element due to different chemical or mechanical processes involved in the creation of the reservoir. [1]: 18
The abundance of the chemical elements is a measure of the occurrences of the chemical elements relative to all other elements in a given environment. Abundance is measured in one of three ways: by mass fraction (in commercial contexts often called weight fraction), by mole fraction (fraction of atoms by numerical count, or sometimes fraction of molecules in gases), or by volume fraction.
Astatine is the rarest naturally occurring element. [j] The total amount of astatine in the Earth's crust (quoted mass 2.36 × 10 25 grams) [108] is estimated by some to be less than one gram at any given time. [8] Other sources estimate the amount of ephemeral astatine, present on earth at any given moment, to be up to one ounce [109] (about ...
Iridium is one of the rarest elements in Earth's crust, with an estimated annual production of only 6,800 kilograms (15,000 lb) in 2023. The dominant uses of iridium are the metal itself and its alloys, as in high-performance spark plugs , crucibles for recrystallization of semiconductors at high temperatures, and electrodes for the production ...
Trace gases are gases that are present in small amounts within an environment such as a planet's atmosphere.Trace gases in Earth's atmosphere are gases other than nitrogen (78.1%), oxygen (20.9%), and argon (0.934%) which, in combination, make up 99.934% of its atmosphere (not including water vapor).
Lanthanum usually occurs together with cerium and the other rare earth elements. Lanthanum was first found by the Swedish chemist Carl Gustaf Mosander in 1839 as an impurity in cerium nitrate – hence the name lanthanum, from the ancient Greek λανθάνειν (lanthanein), meaning 'to lie hidden'. Although it is classified as a rare earth ...
On Earth, it is relatively rare—5.2 ppm by volume in the atmosphere. Most terrestrial helium present today is created by the natural radioactive decay of heavy radioactive elements ( thorium and uranium , although there are other examples), as the alpha particles emitted by such decays consist of helium-4 nuclei .